The present invention relates to a test rotor for balancing machines having a plurality of receptacles for test weights in which fitting surfaces are provided becide the receptacles against which fitting surfaces of the test weights are placed.
Balancing machines, particularly universal balancing machines, are checked for precision with test rotors. Such tests are carried out when the machine is initially accepted by the customer or else later as the need arises. With test rotors, for example, the smallest achievable residual unbalance or the unbalance reduction ratio is tested, whereby the test means, i.e. the test rotor and the test weights, as well as the process sequences are all specified in greater detail in International Standard ISO 2953, incorporated herein by reference. Normally, the test weights or test masses are screw fitted along the circumference of the rotor, and their centers of gravity and masses must be precisely known. ISO 2953, Section 10.2.3, provides information about the necessary precision in the three directions, namely, for the distance of the compensation planes in which the test weights must be arranged, for the compensation radii and for the angle positions of the test weights. An unbalance reduction ratio of 95% translates into a tolerance of 0.5%. Thus, for example, the angle position of the test weights has to be accurate to within 0.29.degree.. For this purpose, in a known manner, the test weights are provided with a fitting collar that is associated with a fitting borehole section at the far end of the screw-in borehole on the rotor. When the test weights are screwed in, the fitting surfaces can seize and the threads can be stripped, which then damages the rotor and frequently renders it unusable.